A variety of ophthalmic surgical procedures require dilation of a pupil of an eye. A full dilation of the pupil provides adequate visualization of ocular structures behind the iris of the eye and facilitates surgery of the lens, vitreous, and retina of the eye. Insufficient dilation of the pupil increases the difficulty in performing ophthalmic surgery. A patient with a small pupil poses a challenge to the surgeon during an eye surgery. A problem that is often encountered is that the diameter of the pupil remains small despite the use of eye drops to dilate the pupil. Atrophy of the pupil dilating muscle or pharmacologic blockage of the pupil dilating muscle from a variety of medications can prevent adequate enlargement of the pupil for eye surgery.
Conventional devices for enlarging the pupil by mechanical means are cumbersome to use, time consuming, and require a high level of skill by a surgeon. Moreover, conventional devices such as iris hooks require multiple incisions to be made in the eye for each hook to retract the pupil in various quadrants. Devices that expand the pupil by retracting the iris at focal points of contact with the margin of the pupil can produce excessive stretching of the iris. Focal points of stretching changes the natural shape of the pupil from a round configuration to a squared configuration. These focal stress points can result in permanent deformities in the shape of the pupil, tears of the pupillary sphincter, bleeding, and/or damage to the iris. Tears of the pupil and damage to the iris can also cause a tonic anisocoria. Moreover, disruption of delicate capillaries at the pupillary margin and the iris may also result in hyphema with elevated intraocular pressure.
Furthermore, conventional pupil expansion devices with sharp edges may damage the iris. Damage from the sharp edges of conventional sharp-edged pupil expansion devices may cause excessive post-operative inflammation and scar tissue. Moreover, complications may ensue from surgical manipulation of a conventional pupil expansion device during removal of the pupil expansion device from the eye. For example, removal of a conventional pupil expansion device can disrupt zonular fibers that stabilize a lens capsule, or cause tears of the pupillary margin that result in a distorted shape of the pupil. Surgical manipulation to remove the pupil expansion device may also disrupt the position of an intraocular lens implant.
Conventional pupil expansion devices are generally bulky and cumbersome to use. These devices are generally difficult to insert, manipulate, and remove through a small incision in the eye. For example, pupil expansion devices that are not foldable and that do not have a coiled structure cannot be easily inserted through a small incision in the eye. Pupil expansion devices that have extensions are particularly difficult to utilize during eye surgery. Moreover, conventional devices for pupillary enlargement are unstable when positioned at the pupillary margin and tend to dislodge during eye surgery. Therefore, there is a need for a pupil expansion device that is structurally simple, remains stable at the pupillary margin during eye surgery, applies a uniform expansile force around the circumference of the pupil to avoid focal stress points, and allows insertion through a small incision.
Hence, there is a long felt but unresolved need for a non-bulky, easy to use pupil dilator and a safe and stable method of pupil dilation that dilates a pupil of an eye along the circumference of the pupil by application of a substantially uniform expansile force. Moreover, there is a need for a pupil dilator that has a configuration that retains the original shape of the pupil and precludes damage to the iris and the pupil during pupil dilation. Furthermore, there is a need for a pupil dilator that can be retained in the eye after surgery to avoid complications associated with removal of the pupil dilator.